Fix tag save issue

Work Item: 17075

--HG--
branch : 1.x

src/Orchard.Web/Modules/Orchard.Tags/Services/TagService.cs

@@ -86,6 +86,10 @@ namespace Orchard.Tags.Services {
 
             // new tag name already existing => merge
             if (tagRecord != null) {
+                // If updating ourselves, ignore
+                if (tagRecord.Id == tagId)
+                    return;
+
                 var tagsContentItems = _contentTagRepository.Fetch(x => x.TagRecord.Id == tagId);
 
                 // get contentItems already tagged with the existing one